CVE-2024-46787

Kernel crash or memory corruption via huge-PMD races

Published Sep 18, 2024 · Updated Aug 5, 2026

Race condition in Linux userfaultfd handling allows local users to crash the kernel or corrupt memory through huge-PMD races. In mm/userfaultfd.c, mfill_atomic() checks pmd_trans_huge() outside a stable lock and mistakes migration, devmap, or replaced PMDs for page tables, reaching BUG_ON() or writing a PTE into non-page-table memory. An unprivileged local process can register its own mapping and race UFFDIO_COPY or UFFDIO_ZEROPAGE against PMD teardown or migration; confirmed outcomes include a repeatable kernel oops, while older kernels expose page-table read and write primitives.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux userfaultfd handling allows local users to crash the kernel or corrupt memory through huge-PMD races. In mm/userfaultfd.c, mfill_atomic() checks pmd_trans_huge() outside a stable lock and mistakes migration, devmap, or replaced PMDs for page tables, reaching BUG_ON() or writing a PTE into non-page-table memory. An unprivileged local process can register its own mapping and race UFFDIO_COPY or UFFDIO_ZEROPAGE against PMD teardown or migration; confirmed outcomes include a repeatable kernel oops, while older kernels expose page-table read and write primitives.

The record

CVE
CVE-2024-46787
Published
Sep 18, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.3
  2. Affected versionversion=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <3c6b4bcf37845c9359aed926324bed66bdd2448d
  3. Affected versionversion=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <71c186efc1b2cf1aeabfeff3b9bd5ac4c5ac14d8
  4. Affected versionversion=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <98cc18b1b71e23fe81a5194ed432b20c2d81a01a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.3; version=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <3c6b4bcf37845c9359aed926324bed66bdd2448d; version=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <71c186efc1b2cf1aeabfeff3b9bd5ac4c5ac14d8; version=c1a4de99fada21e2e9251e52cbb51eff5aadc757 <98cc18b1b71e23fe81a5194ed432b20c2d81a01a

Published CVSS scores

7.8Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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